Burbot Lota lota maculosa numbers in Kootenay Lake and Kootenai River of British Columbia, Idaho, and Montana have diminished due to habitat changes from the construction of Libby Dam. Recent ...implementation of a conservation strategy included aquaculture to supplement the population using a donor stock from a self-sustaining lake population within the watershed. Evaluation of release strategies using telemetry and mark recapture through hoop netting suggests lake-origin Burbot have adapted to the Kootenai system and selected riverine over lacustrine habitat. Previous telemetry work identified good survival and dispersal of released Burbot, and vast dispersal distance and lacustrine use. However, our analysis of a broader telemetry dataset indicated that only 24% of age 1–4 Burbot were detected in the lake. Recapture hoop net data indicated that Burbot residing in the river have growth and survival rates comparable to the historical population. Spawning of hatchery origin fish was detected at historical riverine spawning locations. Other than later spawn timing, our evaluations suggest lake-origin fish are mimicking movement and habitat use of the historical riverine population. This study, in combination with others, provides evidence that Burbot progeny from lacustrine brood stock can successfully survive, grow, disperse, and spawn in a riverine environment.
Burbot, Lota lota (Linnaeus), were illegally introduced into the Green River drainage, Wyoming in the 1990s. Burbot could potentially alter the food web in the Green River, thereby negatively ...influencing socially, economically, and ecologically important fish species. Therefore, managers of the Green River are interested in implementing a suppression program for burbot. Because of the cost associated with the removal of undesirable species, it is critical that suppression programs are as effective as possible. Unfortunately, relatively little is known about the habitat use of non-native burbot in lotic systems, severely limiting the effectiveness of any removal effort. We used hurdle models to identify habitat features influencing the presence and relative abundance of burbot. A total of 260 burbot was collected during 207 sampling events in the summer and autumn of 2013. Regardless of the season, large substrate (e.g., cobble, boulder) best predicted the presence and relative abundance of burbot. In addition, our models indicated that the occurrence of burbot was inversely related to mean current velocity. The efficient and effective removal of burbot from the Green River largely relies on an improved understanding of the influence of habitat on their distribution and relative abundance.
The development of a new protocol for egg fertilization may increase embryo survival and benefit the aquaculture process. In the present study, a new technique of partially adding sperm to activated ...eggs in the artificial fertilization of burbot (Lota lota), ide (Leuciscus idus) and asp (Aspius aspius) eggs was evaluated. If the same volume of sperm was divided into two or three parts and added to eggs in 30–60s intervals, it significantly improved embryo survival at the eyed-egg-stage of development. In the present study, the periodic addition of spermatozoa to eggs affected fertilization (ide and asp) and embryo survival rates (ide, asp and burbot) and might be successfully applied under hatchery conditions.
In systems with multiple piscivores, co-occurrence is dependent on resource partitioning. This is pronounced in oligotrophic northern lakes, which have simple food webs and short open-water seasons. ...We used acoustic telemetry and stable isotopes to quantify habitat and dietary partitioning during thermal stratification among three piscivores that commonly co-occur in Canadian sub-Arctic lakes—burbot (Lota lota), lake trout (Salvelinus namaycush), and northern pike (Esox lucius). Spatial core areas and core habitat niches (space and depth) did not significantly overlap among species. Although burbot and lake trout occupied similar mean daily depths (16.2m and 13.4m, respectively), and water temperatures (5.4°C and 6.9°C, respectively), they were spatially segregated. Burbot were closely associated with the lake bottom on steep drop-offs between the offshore and nearshore zone with moderate substrate complexity, whereas lake trout were located over deep offshore basins and suspended above the lake bottom. Northern pike occupied shallow depths (5.3m) and warmer water (16.5°C) within the nearshore region and were closely associated with bottom substrate of highest complexity. Some significant overlap among spatial home ranges and broad habitat niches indicated that these species interact. However, dietary niches did not significantly overlap at either the core or broad levels, suggesting that species were utilizing spatially diverse food sources. Our results highlight the importance of including depth and space when quantifying resource partitioning among fishes and provide insight into the mechanisms that promote piscivore co-occurrence in northern lakes.
Burbot (Lota lota) are the only true freshwater members of the order Gadiformes and are ideal candidates for intensive cool or coldwater aquaculture. This species has a low temperature requirement, a ...rapid growth rate until onset of sexual maturation, and a high potential market value. Burbot are acclaimed for their thick-flake white flesh fillets, and provide value added products as its roe and liver are both considered delicacies and the skin can be used as a leather product. Burbot perform well on commercial diets, reproduction can be controlled independent of natural season, and sterility can be induced to minimize escapement risks of this species. Additionally, burbot are tolerant of relatively low dissolved oxygen levels, grow well within the same water quality parameters that support rainbow trout (Oncorhynchus mykiss) grow-out, and have been shown to be refractory to many salmonid pathogens. All life stages of burbot can be cultured in captivity and conditions to induce spawning, support larval development, and ensure relatively rapid growth are understood. Trout production facilities in the United States could easily diversify production and increase value to an operation by incorporating burbot into ponds, tanks, or last-use raceways. Although commercial aquaculture of burbot is in its infancy and key economic information is lacking, high consumer and producer interest along with key research advances provide a foundation for successful production of this freshwater cod for the market.
Throughout the Great Lakes, burbot Lota lota are a native, high‐trophic level predator that plays a substantial ecological role. L. lota spawning occurs during wintertime and early spring with ...length‐at‐hatch of 3 mm. Wild‐caught larval L. lota were obtained from three different locations: Lake Superior Keweenaw Peninsula, Ontonagon, Michigan (LSKP), Lake Michigan Midlake Reef (LMMR) and the St. Clair‐Detroit River System (SCDR). Adult spawning L. lota were captured from the Sturgeon River, Pelkie, Michigan (LSSR) and were artificially fertilized; eggs were retained and reared in a laboratory setting. Throughout the first 10 weeks of development, cultured larval L .lota were randomly selected and photographed to measure morphological features. These features were contrasted between cultured larvae and wild‐caught larvae to understand developmental variability in L. lota. From patterns discerned in both cultured and wild‐caught larval L. lota we demonstrated the importance of asynchronous hatching, source location, and variability in larval L. lota development. Comparisons of wild‐caught larval L. lota showed morphological differences, as well as variability in stage and size based on sampling month. These results established that larval L. lota development in the Great Lakes is highly flexible and both species‐specific and environmental processes create the observed variability. The impact of this variability on L. lota populations must be explored to further understand this native Great Lakes species.
Electrical excitability (EE) is vital for cardiac function and strongly modulated by temperature and external K
concentration (K
), as formulated in the hypothesis of temperature-dependent ...deterioration of electrical excitability (TDEE). As little is known about EE of arctic stenothermic fishes, we tested the TDEE hypothesis on ventricular myocytes of polar cod (
) and navaga (
) of the Arctic Ocean and those of temperate freshwater burbot (
). Ventricular action potentials (APs) were elicited in current-clamp experiments at 3, 9 and 15°C, and AP characteristics and the current needed to elicit APs were examined. At 3°C, ventricular APs of polar cod and navaga were similar but differed from those of burbot in having a lower rate of AP upstroke and a higher rate of repolarization. EE of ventricular myocytes - defined as the ease with which all-or-none APs are triggered - was little affected by acute temperature changes between 3 and 15°C in any species. However, AP duration (APD
) was drastically reduced at higher temperatures. Elevation of K
from 3 to 5.4 mmol l
and further to 8 mmol l
at 3, 9 and 15°C strongly affected EE and AP characteristics in polar cod and navaga, but had a lesser effect in burbot. In all species, ventricular excitation was resistant to acute temperature elevations, while small increases in K
severely compromised EE, in particular in the marine stenotherms. This suggests that EE of the heart in these Gadiformes species is resistant against acute warming, but less so against the simultaneous temperature and exercise stresses.
The mechanisms enabling fish tapeworms to avoid proteolytic attacks by digestive enzymes of their fish host have been studied in less detail compared with mammalian cestodes. This study aimed to ...assess the inhibitory ability towards trypsin and chymotrypsin in Eubothrium rugosum, an intestinal parasite of burbot Lota lota, and establish its localization in the tapeworm. To this end, the worms were treated with Triton X‐100 followed by differential centrifugation to isolate the tegumental brush border membrane. The protease inhibitory abilities of the worms were mostly determined by their excretory/secretory products released into the incubation medium. These inhibitory abilities proved to be linked mainly with the brush border fractions. Notably, the per cent inhibition of both studied digestive enzymes (trypsin and chymotrypsin) hardly depended on the duration of the parasite exposure in the incubation medium, probably due to intermittent glycocalyx renewal. Improved knowledge on functions of the excretory/secretory proteins produced by fish tapeworms may contribute to a better understanding of host–parasite relations and development of new approaches to the treatment and prevention of diseases caused by pathogenic helminths.
Infections with microsporidian parasites are described in skeletal muscle of burbot Lota lota from Lake Haukivesi, Finland. Infected myocytes contained spores within sporophorous vesicles (SPVs) in ...contact with host cell cytoplasm, similar to Pleistophora ladogensis in L. lota and smelt Osmerus eperlanus in western Russia and northern Germany. Analysis of small subunit ribosomal RNA (SSU rRNA) gene sequences indicated identity with Myosporidium spraguei in burbot and pike-perch from this lake. The latter is considered a junior synonym of P. ladogensis. Phylogenetic analysis of SSU rRNA sequences resolved the burbot parasite apart from a clade containing the type species P. typicalis, but together with M. merluccius. The parasite is renamed Myosporidium ladogensis (Voronin, 1978) n. comb. Networks of tubular appendages arising from developing meronts and SPVs were associated with degradation of host cell cytoplasm.
Abstract Burbot ( Lota lota : Gadidae) is a difficult species to manage effectively due to its preference for deep‐water habitats and under‐ice spawning behaviour, resulting in a poor understanding ...of its reproductive activity. However, the use of acoustic signalling by burbot as part of their mating system has recently been described and this behaviour may provide a means of investigating questions regarding the spatial and temporal distribution of spawning aggregations using passive acoustic monitoring. We used audio and video recording to confirm that burbot vocalise and that these vocalisations can be detected under field conditions as well as to characterise the relationship between burbot acoustic signalling and spawning behaviour. We also evaluated the feasibility of locating and monitoring burbot spawning aggregations in real time using passive acoustics. Burbot vocalisations were difficult to identify with only about 6% of the recordings containing calls being successfully identified as such in the field. Burbot vocalised more often between sundown and sunrise than during daylight hours. Calls recorded at night tended to be lower frequency, longer duration, and have lower bandwidth than those made during the day. Burbot vocalisations could not be recorded in conjunction with video recordings of spawning activity, indicating that burbot may not call during active spawning, but may use acoustic communication to signal the onset of reproductive readiness and to form pre‐spawning aggregations. While burbot calls were readily identifiable, observers had a difficult time identifying burbot calls in real time under field conditions. Passive acoustic monitoring demonstrates considerable potential as a management tool to locate burbot spawning grounds and identify periods of activity, but may not be an appropriate technique for monitoring spawning activity in real time.
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